Typical computing devices may rely on software agents, such as anti-malware agents, for security. However, it is difficult to keep up with the increasing number of malware attacks on users' devices. To combat the malware threat, there is a trend to protect security-sensitive software by running it inside a Trusted Execution Environment (TEE). TEEs provide a sterile environment that can protect secrets even when other parts of the system are compromised. Examples of TEEs include Intel® Software Guard Extensions (Intel® SGX), secure virtual machines (VMs), and a converged security engine (CSE). The TEE, while useful to protect secrets within the TEE, may not protect I/O data such as user and sensor data that is communicated into and/or out of the secure “container.” The security requirements for trusted I/O vary per use case and device, and may involve flavors and combinations of confidentiality, integrity, liveliness, and replay protection.
On a personal computer platform, securing I/O has several complexities. To protect I/O for a given usage, many input devices may need to be secured because the platform often has multiple devices of the same category connected via different I/O controllers, and a user may dynamically select any one of the connected devices during use. For example, when inputting text, the user may choose to use an embedded keyboard, a USB keyboard, or a Bluetooth (BT) keyboard. The user may also use a touch screen to input data. This means all keyboards and touch input may need to be secured for a usage that requires secure text input. Additionally, I/O devices may be used by secure applications and by regular applications, which means that those devices may be required to switch dynamically from being protected to being in-the-clear and vice versa.